Audio mixer



FIG. 1 is a perspective view of the top, front and left side of an audio mixer showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a bottom plan view thereof.

The portions shown in broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an audio mixer, as shown and described. 